Catheters for delivering medical treatments to remote areas within the body.

Abstract

The pre-flexible wall section of the catheter is manually pre-flexible by a physician along a longitudinal pre-flex range near the distal end of the catheter. The pre-flexible wall section comprises a pre-flexible skeleton (7), which is a discontinuous tubular reinforcement wall with a micro-machined notch pattern (7A). The pre-flexible skeleton comprises several N (N≧2) right-handed spiral struts (21R, 22R), N left-handed spiral struts (21L, 22L), a plurality of ring-shaped struts (23-26), and N connecting nodes (90-99) that are angularly equally spaced at each ring-shaped strut. At each connecting node, the ring-shaped struts, right-handed spiral struts, and left-handed spiral struts are interconnected. The overall cut ratio of the pre-flexible wall section skeleton in the pre-flex range is 45%-85%. The pre-flexible wall section provides well-balanced flexibility in all directions and high shape retention. The catheter can be efficiently fabricated and designed with desirable properties in terms of flexibility, torque, pushability, and lumen integrity.

Description

Technical Field

[0001] The present invention relates to a catheter for delivering medical treatment to a remote site within the body.

[0002] For example, in such medical treatments, such as interventional cardiovascular or neurovascular applications, such a catheter must be angled through the tortuous bends and curves of the (vascular) passageway in order to reach the targeted anatomical structure. Such a catheter requires sufficient flexibility, particularly near its distal end, to navigate such a tortuous path. However, other design aspects must also be considered. For example, the catheter must also be able to provide sufficient torqueability (i.e., the ability to transmit torque applied at the proximal end to the distal end), pushability (i.e., the ability to transmit axial push to the distal end), and structural integrity to perform the intended medical function.

[0003] US2021 / 0023339A1 discloses that a torsion-resistant catheter has at least a first pair of core wires located within the catheter body on opposite sides of the catheter lumen. These core wires have relatively rigid proximal ends but taper toward their distal ends. The tapering structure provides the core wires with some distal flexibility, which helps the catheter advance along the vascular system to the site of interest without twisting. Furthermore, the core wires significantly improve the torsional rigidity of the catheter, so that rotation at the proximal end of the catheter is converted into substantially equivalent rotation at the distal end. If desired, a molded ribbon is provided within the catheter body adjacent to the distal end of the core wire. See, for example, molded ribbons 160 and 162 on the right side of Figure 5 in US2021 / 0023339A1. The molded ribbon can be pre-bent by the physician before the surgical procedure to help the physician advance the catheter along the vascular system. In other words, the molded ribbon can be pre-bent by the physician to the desired deflection angle and maintain that angle. This is useful when the catheter is intended to be used in medical procedures where the vascular system leading to the target site has a commonly known technique angle. Finally, the core wire provides the ability to push the catheter through the vascular system to its original position within the vascular system, without the need to pass through a guidewire in the first place.

[0004] The object of the present invention is to provide an alternative catheter having a “formable” catheter section near the distal end, which can be pre-bent by a physician with well-balanced omnidirectional flexibility and high shape retention, and at the same time, enables the catheter to be reliably fabricated in an efficient manner and designed with favorable properties in terms of the flexibility, torque, pushability and integrity of the lumen structure.

[0005] For that purpose, the present invention provides the catheter described in the attached independent claim 1. Preferred embodiments of the present invention are provided by the attached dependent claims 2 to 9.

[0006] Therefore, the present invention provides a catheter for delivering medical treatment to a remote site within the body. The catheter has a proximal end, a distal end, and a longitudinal direction extending from the proximal end to the distal end. The catheter comprises a tubular catheter wall that surrounds the luminal structure of the catheter and extends proximal along the longitudinal direction from the distal end to at least 100 mm from the distal end. The catheter wall is provided with pre-bendable wall sections that can be manually pre-bend along a pre-bend range in the longitudinal direction, and this pre-bend range extends at least 5 mm from the distal end to the proximal end and 10 mm from the distal end to the proximal end. Pre-bendable wall sections are, - A pre-flexible skeleton that extends at least entirely along the pre-flexible range and provides reinforcement to the catheter wall in the longitudinal direction and in the circumferential direction around the longitudinal direction, wherein the pre-flexible skeleton is a discontinuous tubular reinforcing wall obtained by micro-machining a notch pattern into a completely discontinuous tubular reinforcing wall made of reinforcing material, - An inner liner coaxially surrounded by the pre-bendable skeleton with respect to the centerline of the catheter wall, - An outer laminate coaxially surrounding the pre-bendable skeleton with respect to the centerline of the catheter wall, A skeleton that can be flexed in advance is, -N clockwise spiral supports extending along the direction of a clockwise spiral of number N (N≧2), -N counterclockwise spiral supports extending along each of the N counterclockwise spiral directions, - comprising a plurality of ring-shaped supports each extending along a circular direction, Each of the clockwise spiral supports, the counterclockwise spiral supports, and the ring supports are arranged coaxially with respect to the center line, the N clockwise spiral supports are spaced equally apart from each other by 360 / N of a degree around the center line, the N counterclockwise spiral supports are spaced equally apart from each other by 360 / N of a degree around the center line, the ring supports extend parallel to each other and are spaced apart from each other in the longitudinal direction, and the pre-bendable skeleton has, for each ring support, N connection nodes at N equally spaced angular positions on each of the ring supports involved, and at each connection node, each of the ring supports involved is connected to one of the N clockwise spiral supports and one of the N counterclockwise spiral supports. The overall cut-off ratio of the longitudinal section of the catheter wall's framework in the longitudinal range along the longitudinal direction is: -The volume of all portions within the longitudinal range of the reinforcing material that are cut from the completely discontinuous tubular reinforcing wall according to the micro-machined cut pattern, - Defined as a percentage of the volume of the reinforcing material of the completely discontinuous tubular reinforcing wall, with respect to the volume of all portions within the longitudinal range. Within the pre-bending range, the overall cut-out ratio of the pre-bending wall section's skeletal structure is 45% to 85%.

[0007] In the above-described features of the present invention, the main features of the present invention are: i. A pre-bendable wall section includes a pre-bendable skeleton obtained by microfabricating the cut pattern in such a manner that the pre-bendable skeleton includes an enumerated specific structure of N clockwise spiral supports, N counterclockwise spiral supports, ring supports, and connecting nodes. ii. The overall cutting ratio of the skeletal structure of the pre-flexible wall section is 45% to 85%.

[0008] The main feature (i) relates to the specific structure of the pre-flexible skeleton. In this skeleton, parallel ring-shaped supports provide steel band strength without hindering the pre-flexibility of the pre-flexible wall section. At the same time, N equally spaced spiral supports in two sets oriented in opposite directions provide shape retention and balanced omnidirectional flexibility under the act of pre-flexing by a physician. This pre-flexibility is guided and adjusted by the position of the connection nodes and by the parallel ring-shaped supports. Once flexed to the desired shape, the shape retention of the flexed catheter section remains in perfect form because the pre-flexible skeleton is a triangular structure formed solely by triangles. That is, all connection nodes of the pre-flexible skeleton are the vertices of multiple triangles, where each triangle is formed by three support sections: a left-handed spiral support, a right-handed spiral support, and a ring-shaped support. Such a triangular structure is robust.

[0009] The main feature (ii) relates to the excision ratio of the entire skeleton of the pre-flexible wall segment. According to the lower limit specified by main feature (ii), ensuring that the excision ratio is not lower than 45% prevents the pre-flexibility of the wall segment from becoming too cumbersome for the physician. According to the upper limit specified by main feature (ii), ensuring that the excision ratio of the entire skeleton of the pre-flexible wall segment is 85% or less prevents the wall segment from becoming unwieldy after flexion.

[0010] Furthermore, it will be readily apparent that the pre-flexible skeleton provides the pre-flexible wall section with very good torque, pushability, and integrity of the lumen structure. Other longitudinal sections of the catheter can be designed in many different ways and can be firmly connected to or integrated with the pre-flexible wall section having the pre-flexible skeleton. Thus, the present invention enables catheters to be reliably manufactured in an efficient manner and designed with desirable properties in terms of flexibility, torque, pushability, and integrity of the lumen structure.

[0011] It should be noted that manufacturing the pre-flexible wall section of the present invention with such a high overall skeleton cut-off ratio (at least 45%) requires the measures of the present invention to solve several problems. This is because the inner liner of catheters with skeletons for many applications is typically a tube made of, for example, PTFE (polytetrafluoroethylene, e.g., Teflon®), PVDF (polyvinylidene fluoride, e.g., Kynar®), or HDPE (high-density polyethylene), which is inserted axially into the skeleton during the manufacture of the catheter and then expands relative to the skeleton by expansion and heat. With such a high cut-off ratio, for example, a tube made of PTFE, PVDF, or HDPE that expands relative to the skeleton will have the problem of bulging outward from the large cut-off in the skeleton material and / or breaking under expansion pressure. Another problem, especially for skeletons made from lower-strength materials, is that the skeleton may deform and / or crack and / or break significantly under expansion pressure due to the fact that the skeleton is significantly weakened by the large cut-off in the skeleton material.

[0012] In connection therewith, the present invention is based, in particular as disclosed herein, on the novel insight that the problem can be solved by temporarily introducing a heat-shrinkable outer tube over the outer surface of a pre-flexible skeleton during the manufacture of the catheter according to the present invention, so as a result the heat-shrinkable outer tube temporarily closes a notch in the skeleton material during the expansion of the inner liner by expansion and heat, and at the same time the heat-shrinkable outer tube temporarily reinforces the pre-flexible skeleton during the expansion of the inner liner by expansion and heat. After the inner liner has been successfully expanded against the skeleton and the catheter under construction has cooled, the temporary heat-shrinkable outer tube can be removed from the outside of the skeleton and replaced with a final outer laminate on the outside of the skeleton.

[0013] Alternatively, as disclosed herein, another novel insight is that, in the case of a high overall cut ratio (at least 45%) of the pre-flexible wall section of the catheter wall of the catheter according to the present invention, the problem can be solved by performing the following manufacturing steps to assemble the inner liner and outer laminate to the skeleton: First, a tubular base layer of fluorinated ethylene propylene (FEP) is extruded, and the inner liner is extruded onto the base layer. Next, the FEP base layer is axially inserted into the skeleton together with the inner liner. Next, the outer laminate is slid onto the outside of the skeleton. Subsequently, a temporary heat-shrinkable outer FEP tube is slid onto the outer laminate, and the entire assembly is heated. During heating, the temporary heat-shrinkable outer FEP tube provides high compression to the assembly of the inner liner, skeleton, and outer laminate. After the catheter under construction has cooled, the temporary heat-shrinkable outer tube can be removed from the outside of the skeleton, and the FEP base layer can be axially pulled out from the assembly, taking advantage of the favorable properties of FEP with respect to being pulled out. Therefore, a very close fit of the inner liner to the inside of the skeleton is obtained.

[0014] It should be noted that the use mentioned immediately before such an extruded FEP base layer is a more effective and far less expensive alternative to the conventional use of a temporarily silver-plated copper wire that is axially drawn out from the inner liner of the catheter under construction at the end of the manufacturing subprocess.

[0015] Another advantage of the present invention is that, thanks to the high overall cut ratio (at least 45%) of the pre-flexible wall section of the catheter wall of the catheter according to the present invention, and thanks to the insights referred to herein as disclosed herein, the present invention enables the efficient embedding of radiopaque elements (e.g., radiopaque markers) into the catheter wall, for the reason that the radiopaque elements can be fully positioned within the space of the cut pattern, which is bounded by the pre-flexible skeleton, inner layer, and outer laminate.

[0016] In a preferred embodiment of the catheter according to the present invention, the pre-flexion range extends at least 0.5 mm proximally from the distal end and 15 mm proximally from the distal end. Thus, the pre-flexible skeleton extends distally, closer to the distal end, which increases the physician's options for shaping a catheter closer to the distal end.

[0017] More preferably, the pre-bending range extends at least from the distal end to 20 mm proximally from the distal end, which increases the physician's options for shaping the catheter further.

[0018] In another preferred embodiment of the catheter according to the present invention, the cut-off ratio of the entire skeleton of the pre-flexible wall section within the pre-flex range is 60% to 80%. This further facilitates the moldability of the wall section for the physician and further improves the shape retention after molding.

[0019] More preferably, the overall cut-off ratio of the pre-bendable wall section skeleton within the pre-bend range is 70% to 78%. This further facilitates the moldability of the wall section for the physician and further improves the shape retention after molding.

[0020] In another preferred embodiment of the catheter according to the present invention, the radiopaque element is embedded in the catheter wall in such a way that the radiopaque element is located within a space of a notch pattern, and the space is bounded by a pre-flexible skeleton, an inner layer, and an outer laminate.

[0021] The catheter according to the present invention can be embodied as a rapid exchange catheter having a tubular catheter wall as a distal rapid exchange tubular segment spaced apart from the proximal end of the rapid exchange catheter.

[0022] Such a rapid exchange catheter has a proximal catheter segment proximal to the distal rapid exchange tubular segment, which can be, for example, a push rod connected to the distal rapid exchange tubular segment. Such a push rod can advantageously have a round design with a diameter ≦ 0.40 mm in order to maintain a 1:1 torque property from the proximal end to the distal end. Such a 1:1 torque property is highly desirable for this type of device because the physician needs to be able to accurately maneuver the catheter towards the target site such as a bend or side branch in the vascular access.

[0023] Alternatively, the catheter according to the present invention can be embodied as an over-the-wire (OTW) catheter, and the tubular catheter wall and lumen structure of the catheter all extend along the longitudinal direction from the proximal end to the distal end.

[0024] Such an over-the-wire catheter can advantageously have an over-the-wire catheter skeleton, which extends along the longitudinal direction from the proximal end to the distal end and provides reinforcement of the catheter wall in the longitudinal direction and in the circumferential direction around the longitudinal direction. The over-the-wire catheter skeleton is a discontinuous tubular reinforcement wall obtained by micro-machining a cut pattern within a completely non-discontinuous tubular reinforcement wall made of a reinforcing material. Thus, in this case, the pre-bendable skeleton of the pre-bendable wall section is a section of the over-the-wire catheter skeleton. Preferably, the over-the-wire catheter skeleton is designed to maintain a 1:1 torque property from the proximal end to the distal end of the over-the-wire catheter. Alternatively to the over-the-wire skeleton, the over-the-wire catheter can also be designed using a braided or wire coil structure for maintaining, for example, a 1:1 torque property in the longitudinal section outside the pre-bendable range of the pre-bendable skeleton.

[0025] In another preferred embodiment of the catheter according to the present invention, the N right-handed helical struts and the N left-handed helical struts each have the same pitch compared to each other, the pitch being defined as the distance measured along the longitudinal direction of one helical winding of the relevant helical strut, the pre-bending range having at least one continuous sub-range having a length equal to the pitch, and the pre-bendable skeleton having, within the continuous sub-range, a number of the ring-shaped struts equal to N multiplied by 2.

[0026] Hereinafter, the present invention will be further elucidated with reference to non-limiting embodiments and to the schematic views of the accompanying drawings shown below, the accompanying drawings showing the following.

Brief Description of the Drawings

[0027] [Figure 1] An example of an embodiment of a catheter according to the present invention is shown in a longitudinal side view. In FIG. 1, the pre-bending range of the pre-bendable wall section of the catheter wall is indicated by square brackets. In the catheter embodiment of FIG. 1, the number N mentioned above is equal to 2 (N = 2). [Figure 2] A perspective view shows a longitudinal section of the pre-bendable skeleton of the pre-bendable wall section of the catheter of FIG. 1. [Figure 3A] A short longitudinal section of the pre-bendable wall section of the catheter of FIG. 1 is shown. The longitudinal section shown comprises a part of the pre-bendable skeleton, and the figure shown is a longitudinal cross-section including the center line of the catheter wall. [Figure 3B] A cross-section through a longitudinal section of the pre-bendable wall section of FIG. 3A is shown, the cross-section shown being perpendicular to the center line of the catheter wall. [Figure 4] A short longitudinal section of the pre-bendable skeleton of the pre-bendable wall section of the catheter of FIG. 1 is shown. The figure shown is a top view of the longitudinal section in a virtual "unrolled tube" state of the longitudinal section. [Figure 5A]Again, Figure 1 shows the pre-flexible wall section of the catheter, specifically the short longitudinal section of the pre-flexible skeleton, but this time the figure shown is a longitudinal side view. [Figure 5B] Again, Figure 5A shows a longitudinal side view, but this time the longitudinal section is bent as a result of the physician pre-bending the pre-bendable wall section of the catheter shown in Figure 1. [Figure 6] An example of the distal skeleton of the distal section of the tubular catheter according to the present invention is shown in a side view similar to the side view in Figure 5A, and the distal skeleton in Figure 6 is an interconnection of the ends of the pre-bendable skeleton in Figures 1-5, the second skeleton and the third skeleton. [Figures 7A-7E] Figure 6 shows details of the second skeleton. [Figures 8A-8C] Figure 6 shows details of the third skeleton. [Figure 9] A short longitudinal section of an example of an alternative embodiment of the pre-flexible skeleton of the catheter according to the present invention is shown in a diagram similar to that of Figure 4, where in the alternative embodiment of the pre-flexible skeleton of Figure 9, the number N mentioned above is equal to 3 (N=3).

[0028] The reference numerals used in the embodiments of Figures 1-8 refer to the parts and aspects of the present invention, as well as related parts and aspects, as follows: 1--------------Catheter 2--------------Tubular catheter wall 3--------------Lumen structure 4--------------Proximal end 5--------------Distal end 6--------------Distal skeleton 7--------------A skeleton that can be flexed in advance 7A------------Cutting Pattern 8--------------Inner liner 9--------------Outer lamination 10------------Longest direction 11------------Circumferential direction 12------------Center line 14------------Pre-bendable wall section 15------------Pre-flexion range 16------------Second range 17------------Third range 21L, 22L --- Two counterclockwise spiral supports 21R, 22R --- Two clockwise spiral supports 23-26--------Four ring-shaped supports 44------------Second skeleton 45------------The third skeleton 51~54-------Spiral part 61~66-------Spiral slots 90-99--------10 connected nodes

[0029] The reference numerals used in the alternative embodiment in Figure 9 refer to the parts and aspects of the present invention, as well as related parts and aspects, as follows: 107----------------------A skeleton capable of pre-flexion 107A--------------------Cutting Pattern 110----------------------Long side 111----------------------Circumferential direction 121L, 122L, 123L --- Three counter-clockwise spiral supports 121R, 122R, 123R --- Three clockwise spiral supports 123-128-----------------6 ring-shaped supports 140-160-----------------21 connected nodes

[0030] Based on the above introductory description, including a brief description of the drawings, and based on the reference numerals listed above used in Figures 1-9, the embodiments in Figures 1-8 and the alternative embodiment in Figure 9 are readily apparent in most respects. Further explanation is given below.

[0031] Figure 1 shows a catheter 1 having a longitudinal direction 10, a proximal end 4, and a distal end 5. Figure 1 further shows the pre-bending range 15 of the pre-bending wall section 14 of the catheter wall 2.

[0032] In the embodiments shown in Figures 1-8, the number N mentioned above is equal to 2 (N=2). This means that in the embodiments shown in Figures 1-8, the pre-bendable skeleton 7 comprises two clockwise spiral supports that are equally spaced 180 degrees apart from each other, and two counterclockwise spiral supports that are equally spaced 180 degrees apart from each other.

[0033] The perspective view in Figure 2 shows that the pre-flexible skeleton 7 of the pre-flexible wall section 14 of the catheter 1 in Figure 1 has two left-handed spiral supports 21L and 22L, two right-handed spiral supports 21R and 22R, and at least mutually parallel ring-shaped supports 23 to 26.

[0034] Figures 3A-3B show that the pre-bendable wall section 14 has a skeleton 7 including a notch pattern 7A, as well as an inner liner 8 and an outer laminate 9. In the example of Figures 3A-3B, the lumen structure 3 of the catheter 1 is a single lumen structure. Alternatively, the catheter according to the present invention may have multiple lumen structures.

[0035] Figure 4 shows a short longitudinal section of the pre-flexible skeleton 7 of the pre-flexible wall section 14 of catheter 1. In Figure 4, the diagram shown is a top view of the longitudinal section in a hypothetical "unfolded tube" state. To explain the term "unfolded tube," note that the pre-flexible skeleton is a tubular wall (more specifically, a discontinuous tubular reinforcement wall), and that such a tubular wall can be virtually unfolded into a perfectly straight state by virtually unfolding the tubular wall onto a completely straight plane after a hypothetical straight cut parallel to the centerline of the catheter is made along the entire length of the tubular wall. In Figure 4, this hypothetical straight cut is a straight line passing through the connection nodes 90, 91, and 92 of the pre-flexible skeleton 7. In Figure 4, reference numerals 90, 91, and 92 are shown both at the bottom and top of Figure 4 because, as shown in the perspective view of Figure 2, the complete straight state of Figure 4 is "rolled up" again to form the tubular state of the pre-bent skeleton 7, and the locations indicated by these reference numerals 90, 91, and 92 will be joined.

[0036] From Figure 4, -The counterclockwise spiral support column 22L extends continuously from connection node 90 to connection node 93, from connection node 96 to connection node 99, and to connection node 92. -The counterclockwise spiral support column 21L extends continuously from connection node 95 to connection node 98, from connection node 91 to connection node 94, and to connection node 97. - The clockwise spiral support column 21R extends continuously from connection node 95 to connection node 93, from connection node 91 to connection node 99, and to connection node 97. -It can be seen that the clockwise spiral support column 22R extends continuously from connection node 90 to connection node 98, from connection node 96 to connection node 94, and to connection node 92.

[0037] From Figure 4, it can be inferred that the two clockwise spiral supports 21R and 22R are angularly separated from each other by 180 degrees around the center line 12, the two counterclockwise spiral supports 21L and 22L are angularly separated from each other by 180 degrees around the center line 12, and the ring-shaped supports 23, 24, 25, and 26 extend parallel to each other and are separated from each other in the longitudinal direction 10.

[0038] From Figure 4, it can be further inferred that the pre-bendable skeleton 7 has two connection nodes for each of the illustrated ring-shaped supports 23, 24, 25, and 26, located at two positions directly opposite each other in the diametrical direction of each related ring-shaped support, and that at each connection node, each related ring-shaped support is connected to one of the two clockwise spiral supports 21R and 22R, and one of the two counterclockwise spiral supports 21L and 22L.

[0039] Figure 4 clearly illustrates that the pre-bendable frame 7 is a triangular structure formed solely from triangles. That is, all connection nodes 90-99 of the pre-bendable frame 7 are vertices of multiple triangles, where each triangle is formed by three support divisions: a counterclockwise spiral support, a clockwise spiral support, and a ring-shaped support. Such a triangular structure is robust and allows for desirable shape retention.

[0040] Figures 5A and 5B illustrate that when a physician pre-bends the pre-flexible wall section 14 of catheter 1, the triangular structure of the pre-flexible skeleton 7 deforms only slightly. Parallel ring-shaped supports (including illustrated ring-shaped supports 23-26) provide steel band strength without hindering the pre-flexibility of the pre-flexible wall section. Simultaneously, this pre-flexibility is guided and regulated by the position of the connecting nodes (including illustrated connecting nodes 90-99) and by the parallel ring-shaped supports. Clearly, the multi-triangular features of the pre-flexible skeleton 7 remain intact even after pre-bending, and therefore the good shape retention of the skeleton is also preserved.

[0041] In the illustrated example, the pre-flexible frame 7 has the following dimensions. The pre-flexible range 15 extends from the distal end 5 to 20.0 mm proximally from the distal end 5. Thus, the pre-flexible frame 7 has a length of 20.0 mm in the longitudinal direction 10. The pre-flexible frame 7 has an outer diameter of 0.635 mm and an inner diameter of 0.510 mm. The pitch of each of the two right-handed spiral supports 21R, 22R and the two left-handed spiral supports 21L, 22L is 1.00 mm, and the pitch is defined as the distance measured along the longitudinal direction 10 of one spiral winding of the spiral supports involved. Thus, in Figure 4, the pitch of each spiral support is equal to the distance measured along the longitudinal direction 10 between the two centers of the two connecting nodes 90 and 92, respectively. The mutually parallel ring-shaped supports are spaced apart from each other by 0.250 mm when measured along the longitudinal direction 10. The width of each spiral and ring-shaped support is 0.030 mm when measured in the "unfolded tube" state of the pre-bendable skeleton 7 shown in Figure 4. The cut-out ratio of the entire skeleton of the pre-bendable wall section 14 in the pre-bend range 15 is approximately 76%.

[0042] Note that in the illustrated example, the pre-flexible skeleton 7 terminates at the distal end 5 of the catheter 1. However, alternatively, the medial liner 8 and / or lateral laminate 9 may extend slightly distally beyond the pre-flexible skeleton 7, leaving the distal end 5 intact.

[0043] Figure 6 shows the pre-bendable skeleton 7 in the pre-bend range 15, together with the second skeleton 44 and the third skeleton 45. The three skeletons 7, 44, and 45 are continuously interconnected in a way that connects their ends along the longitudinal direction 10 to form the distal skeleton 6 of the distal section of the tubular catheter wall 2. The second skeleton 44 extends within the second range 16, which extends along the longitudinal direction 10 from 20.0 mm proximal to the distal end 5 to 100.0 mm proximal to the distal end 5. The third skeleton 45 extends within the third range 17, which extends along the longitudinal direction 10 from 100.0 mm proximal to the distal end 5 to 150.0 mm proximal to the distal end 5. The second skeleton 44 and the third skeleton 45 are shown in more detail in Figures 7 and 8, respectively.

[0044] Here, we refer to Figures 7A–7E illustrating the second skeleton 44. The second skeleton 44 extends along the longitudinal direction 10 for a length of 80.0 mm in the second range 16 (see Figure 6). Each of Figures 7A–7E shows the second skeleton 44 along only a portion of the length mentioned immediately above. Figure 7A shows a portion of the second skeleton 44 in a longitudinal side view. Figures 7B and 7C show two other portions of the second skeleton 44 in a longitudinal side view, with the portion in Figure 7B located distal to the portion in Figure 7A, and the portion in Figure 7C located proximal to the portion in Figure 7A. Figure 7D is a perspective view of the second skeleton 44. Figure 7E shows a top view of the longitudinal section of the second skeleton 44 in a virtually unfolded tubular state (the term "unfolded tubular" was explained above with reference to Figure 4). Figures 7D-7E show that the second skeleton 44 consists of four helical sections, two of which are clockwise helical sections 51 and 52, and two of which are counterclockwise helical sections 53 and 54. The two clockwise helical sections 51 and 52 intersect with the two counterclockwise helical sections 53 and 54 at several nodes of the second skeleton 44.

[0045] In Figures 7B-7C, several dimensions are shown by numerical values ​​that should be interpreted in millimeters (mm). Figures 7B-7C help illustrate an embodiment in which the thickness of the helical portion of the second skeleton 44 gradually decreases distally along the longitudinal direction. Thereafter, the flexibility of the second skeleton 44 of the catheter wall 2 gradually increases distally along the longitudinal direction 10.

[0046] Here, we refer to Figures 8A–8C, which show the third skeleton 45 in a longitudinal side view. The third skeleton 45 extends along the longitudinal direction 10 for a length of 50.0 mm in the third range 17 (see Figure 6). Each of Figures 8A–8C shows the third skeleton 45 along only a portion of the length mentioned above. The portion in Figure 8C is located distal to the portion in Figure 8A. The portion in Figure 8B is located distal to the portion in Figure 8C. The third skeleton 45 has several helical slots that are interconnected in a way that connects end to end along the longitudinal direction 10. Each helical slot has a slight helical winding. For example, Figure 8A shows helical slots 61 and 62, Figure 8C shows helical slots 63 and 64, and Figure 8B shows helical slots 65 and 66. Two interconnected slots of the helical slots each have opposite winding directions relative to each other. Such interconnections of two oppositely oriented helical slots are shown in the longitudinal center of Figures 8A–8C. Figures 8A–8C further help illustrate the gradual decrease in the pitch of the helical slots for distally succeeding helical slots along the longitudinal direction 10. As a result of this decreasing pitch, the overall cut ratio of the catheter wall 2 skeleton in the third range 17 gradually increases distally, and the flexibility of the catheter wall 2 in the third range 17 gradually increases distally along the longitudinal direction.

[0047] The three interconnected skeletons 7, 44, and 45 of the distal skeleton 6 in Figure 6 can be manufactured as a single unit by microfabrication of a notched pattern into a completely non-discontinuous tubular reinforcing wall made of reinforcing material.

[0048] A tubular catheter wall having a pre-flexible skeleton 7 or a larger distal skeleton 6 may be part of a rapid exchange catheter having a tubular catheter wall as a distal rapid exchange tubular segment spaced apart from the proximal end of the rapid exchange catheter. Alternatively, such a tubular catheter wall may be part of an over-the-wire (OTW) catheter, where the tubular catheter wall extends along the longitudinal direction from the proximal end to the distal end.

[0049] As noted, the embodiments in Figures 1-8 are embodiments where N=2. More specifically, the embodiments in Figures 1-8 are examples of preferred embodiments of the catheter according to the present invention, where N (i.e., 2) right-handed helical struts (21R, 22R) and N (i.e., 2) left-handed helical struts (21L, 22L) each have the same pitch relative to one another, the pitch is defined as the distance measured along the longitudinal direction of one helical winding of the helical struts involved, the pre-flexible range has at least one continuous sub-range having a length equal to the pitch, and it should be further noted that the pre-flexible skeleton has a number of ring struts (23, 24, 25, 26) in the continuous sub-range that is N multiplied by 2 (i.e., 4). This is evident from Figure 4, which is a short longitudinal section of the pre-flexible skeleton 7, the short longitudinal section corresponding to such a continuous sub-range having a length equal to the pitch. Figure 4 shows that the pre-bendable skeleton 7 has 10 connection nodes (90-99) within the continuous sub-range.

[0050] Here, we refer to Figure 9, which shows a pre-flexible skeleton 107 as an alternative embodiment to the pre-flexible skeleton 7 of Figure 4. In the alternative pre-flexible skeleton 107 of Figure 9, the number N mentioned above is equal to 3 (N=3). This means that in the embodiment of Figure 9, the pre-flexible skeleton 107 comprises N (i.e., 3) clockwise spiral supports (121R, 122R, 123R) that are equally spaced at an angle of 120 degrees relative to each other, and N (i.e., 3) counterclockwise spiral supports (121L, 122L, 123L) that are equally spaced at an angle of 120 degrees relative to each other.

[0051] In the catheter embodiments of Figures 1-8, when the pre-flexible skeleton 7 is replaced with an alternative pre-flexible skeleton 107, an example of a preferred embodiment of the catheter referred to above according to the present invention is provided more specifically, where N (i.e., 3) right-handed spiral struts and N (i.e., 3) left-handed spiral struts each have the same pitch relative to one another, the pitch is defined as the distance measured along the longitudinal direction of one spiral winding of the spiral struts involved, the pre-flex range has at least one continuous sub-range having a length equal to the pitch, and it should be further noted that the pre-flexible skeleton has a number of such ring struts (123, 124, 125, 126, 127, 128) in the continuous sub-range that is N multiplied by 2 (i.e., 6). This is evident from Figure 9, which is a short longitudinal section of the pre-flexible skeleton 107, the short longitudinal section corresponding to such continuous sub-range having a length equal to the pitch. Figure 9 shows that the pre-bendable skeleton 107 has 21 connection nodes (140-160) in the continuous sub-range.

[0052] It will be readily apparent to the reader of this disclosure how, from the exemplary embodiments of the catheter according to the present invention described above for N=2 and N=3, respectively, an example of an embodiment of the catheter according to the present invention for N≧4 can be designed similarly.

[0053] The present invention can be put into practice using a variety of structures, materials, shapes, and dimensions of the pre-flexible skeleton, inner liner, and outer laminate of a catheter, as well as a variety of additional features and accessories of the catheter, such as a variety of structures, materials, shapes, and dimensions of the skeleton, inner liner, and outer laminate, and a variety of additional features and accessories used in known catheters for delivering medical treatment to remote sites within the body, as long as the catheter is within the scope of the attached claims.

[0054] The following general note is made regarding the total skeletal cut-off ratio: Anywhere in a longitudinal section of the catheter wall that is continuous in the longitudinal direction, if the catheter wall has a completely discontinuous tubular metal reinforcement wall, for example in the form of a completely discontinuous metal hypotube, then that longitudinal section has a total skeletal cut-off ratio of 0%.

[0055] It should be further noted that, according to the present invention, typical dimensions of some parts and embodiments of the present invention, and the applicable practical range of such dimensions, may be as follows when the catheter is a microcatheter for interventional cardiovascular or neurovascular applications: The effective length of the catheter (measured from the distal end of the catheter hub) may be in the range of 130 cm to 160 cm, and can typically be 135 cm. The maximum outer diameter of the pre-flexible wall section of the tubular catheter wall of the catheter may be in the range of 0.60 mm to 1.20 mm, and can typically be 0.75 mm, but it should be noted that the term "maximum" in the term "maximum outer diameter" refers to the maximum value, taken into consideration over the entire length of the pre-flexible wall section. The minimum inner diameter of the pre-flexible wall section of the tubular catheter wall can be in the range of 0.36 mm to 0.55 mm, and is typically 0.45 mm. However, it should be noted that the term "minimum" in "minimum inner diameter" refers to the minimum value considered over the entire length of the pre-flexible wall section. For example, the following typical combinations of the maximum outer diameter and minimum inner diameter of the pre-flexible wall section are possible: a maximum outer diameter of 0.75 mm combined with a minimum inner diameter of 0.45 mm, a maximum outer diameter of 1.20 mm combined with a minimum inner diameter of 0.55 mm, or a maximum outer diameter of 0.60 mm combined with a minimum inner diameter of 0.36 mm.

[0056] However, the present invention can be embodied in various other catheters for delivering medical treatments to distant sites within the body, which may be nonvascular catheters and / or non-microcatheters, such as catheters for delivering medical treatments to renal blood vessels, fallopian tubes, and other such blood vessels and sites. In such cases, the typical dimensions of some parts and embodiments of the present invention, and the applicable practical range of such dimensions, may differ from the range mentioned above for microcatheters for interventional cardiovascular or neurovascular applications.

Claims

1. A catheter (1) for delivering medical treatment to a remote site in the body, The catheter has a proximal end (4), a distal end (5), and a longitudinal direction (10) extending from the proximal end to the distal end. The catheter comprises a tubular catheter wall (2) that surrounds the tubular structure (3) of the catheter and extends proximal from the distal end (5) along the longitudinal direction, for at least 100 mm proximal to the distal end. The catheter wall (2) is provided with pre-bendable wall sections (14) that can be fully pre-bend along the pre-bend range (15) in the longitudinal direction, and the pre-bend range extends at least 5 mm proximal to the distal end and 10 mm proximal to the distal end (5). The aforementioned pre-bendable wall section (14) is - A pre-flexible skeleton (7) that extends at least along the entire pre-flexible range and provides reinforcement to the catheter wall (2) in the longitudinal direction (10) and in the circumferential direction (11) around the longitudinal direction (10), wherein the pre-flexible skeleton (7) is a discontinuous tubular reinforcing wall obtained by micro-machining a notch pattern (7A) into a completely discontinuous tubular reinforcing wall made of reinforcing material, - The inner liner (8) is coaxially surrounded by the pre-bendable skeleton (7) with respect to the center line (12) of the catheter wall (2), - The catheter wall comprises an outer laminate (9) that coaxially surrounds the pre-bendable skeleton (7) with respect to the center line (12) of the catheter wall, The aforementioned pre-flexible skeleton is - N clockwise spiral supports (21R, 22R) extending along a clockwise spiral direction of number N (N≧2), - N counterclockwise spiral supports (21L, 22L) extending along each of the N counterclockwise spiral directions, - comprising a plurality of ring-shaped support columns (23-26) each extending along a circular direction, Each of the aforementioned clockwise spiral supports (21R, 22R), counterclockwise spiral supports (21L, 22L), and ring-shaped supports (23-26) is arranged coaxially with respect to the center line (12), with N clockwise spiral supports spaced equally apart from each other by 360 / N of a degree around the center line (12), and N counterclockwise spiral supports spaced equally apart from each other by 360 / N of a degree around the center line, and the ring-shaped supports extend parallel to each other. The pre-bendable skeleton (7) is located and is spaced apart from each other in the longitudinal direction, and each of the ring-shaped supports has N connecting nodes (90-99) at N angularly equally spaced positions on each of the related ring-shaped supports, and at each connecting node (90-99), each of the related ring-shaped supports (23-26) is connected to one of the N right-handed spiral supports (21R, 22R) and one of the N left-handed spiral supports (21L, 22L). The overall cutting ratio of the skeletal structure of the longitudinal section of the catheter wall (2) in the longitudinal range along the longitudinal direction (10) is, - The volume of all portions of the reinforcing material within the longitudinal range that are cut from the completely discontinuous tubular reinforcing wall according to the micro-machined cut pattern (7A), - Defined as a percentage of the volume of the reinforcing material of the completely non-discontinuous tubular reinforcing wall, with respect to the volume of all portions within the longitudinal range. A catheter in which the ratio of the entire skeleton of the pre-bendable wall section (14) in the pre-bend range (15) is 45% to 85%.

2. The catheter (1) according to claim 1, wherein the pre-bending range (15) extends at least between 0.5 mm proximal to the distal end (5) and 15 mm proximal to the distal end (5).

3. The catheter (1) according to claim 2, wherein the pre-bending range extends at least between the distal end (5) and 20 mm proximal to the distal end (5).

4. The catheter (1) according to any one of the prior claims, wherein the ratio of the total skeleton of the pre-bendable wall section (14) in the pre-bend range (15) is 60% to 80%.

5. The catheter (1) according to claim 4, wherein the ratio of the total skeleton of the pre-bendable wall section (14) in the pre-bend range (15) is 70% to 78%.

6. A catheter (1) according to any one of the prior claims, wherein the radiopaque element is embedded in the catheter wall (2) such that the radiopaque element is located within the space of the notch pattern (7A) and the space is bounded by the pre-flexible skeleton (7), the inner layer (8), and the outer laminate (9).

7. The catheter (1) according to any one of the prior claims, wherein the catheter is a rapid exchange catheter, and the rapid exchange catheter has the tubular catheter wall (2) as a distal rapid exchange tubular segment spaced apart from the proximal end (4) of the rapid exchange catheter.

8. The catheter (1) according to any one of claims 1 to 6, wherein the catheter is an over-the-wire (OTW) catheter, and the tubular catheter wall (2) and the lumen structure (3) of the catheter extend along the longitudinal direction (10) from the proximal end (4) to the distal end (5).

9. A catheter (1) according to any one of the prior claims, wherein N clockwise spiral supports (21R, 22R) and N counterclockwise spiral supports (21L, 22L) each have the same pitch when compared to one another, the pitch is defined as the distance measured along the longitudinal direction (10) of one spiral winding of the spiral supports involved, the pre-bend range (15) has at least one continuous sub-range having a length equal to the pitch, and the pre-bendable skeleton (7) has a number of ring supports equal to N multiplied by 2 within the continuous sub-range.

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